Pressure-induced transformations of hexagonal molybdenum oxide (h-MoO₃) nanorods prepared by a hydrothermal method were investigated in situ using synchrotron X-ray diffraction and Raman scattering in a diamond anvil cell up to 62 GPa under ambient temperature. We observed that h-MoO₃ nanorods present a pressure-induced amorphization (PIA) process upon compression to 16 GPa, a critical pressure higher than for h-MoO₃ microcrystal. Our data provide evidence that a new amorphous-amorphous phase transition occurs at about 34 GPa, resulting in a high-density amorphous (HDA) form. Upon decompression, the HDA form was maintained at ambient conditions. SEM images of the samples submitted to different hydrostatic pressures revel that their pristine nanorods shape is loss by in situ fracture process, between 16-30 GPa of applied pressure. The bulk modulus of the nanostructured h-MoO₃ phase was determined by fitting of the volume by a third-order Birch–Murnaghan equation of state, which yields a bulk modulus value of B₀ = 49.8 ± 2.0 GPa, with B₀’ = 5. This study is the first to demonstrate that h-MoO₃ present both amorphization and polyamorphism under high-pressure conditions.